Soil erosion is a serious problem which commonly results frown water flow at the interface of land and water such as on the side of a riverbed or the like. Soil erosion can also result from rainfall as it proceeds through a basin or the like which typically empties into a river.
Trees, grass and other forms of vegetation and the like naturally inhibit erosion. The root systems of the grass, vegetation and the like serve to consolidate the underlying soil and prevent soil erosion. It is common, however, that areas where water is continually flowing are subject to relatively high hydraulic load applications and the natural methods of inhibiting soil erosion will not always suffice. Many times, vegetation growth cannot be accomplished quickly enough to prevent erosion.
Various revetment systems have been used to augment or replace vegetation as an erosion barrier. In one form, a loose revetment barrier is typically accomplished by dumping large non-uniform chunks of concrete over an area. Relative high hydrodynamic forces acting on these revetment systems are generated by the flow of a river over the concrete chunks. A shear force acts in the direction of river flow over the revetment. A lift force acts generally perpendicular. Because the chunks of concrete are of non-uniform or random size, it is often difficult to determine the hydrodynamic aspects to counteract such forces acting against the revetment, thus detracting from an engineered system. Moreover, the concrete chunks commonly used are of random size and therefore complicate the engineered hydrodynamic interaction and static of the system.
Soil erosion prevention blocks and other revetment blocks are well known in the art. In one form, a plurality of erosion blocks are strung together as by cables laced through the blocks to form a mat of concrete. These known mats of strung-together concrete blocks are expensive. The difficulty and cost of installation of such mats also weigh against this type of system.
The permeability, static friction, dynamic friction, surface roughness, and weight per square foot of such grid matrix systems are important engineering concerns to inhibiting displacement of the blocks under the influence of the hydrodynamic loading of the river or waters flowing thereover, and to a limited degree thereunder. Thus, the need to adjust the permeability, and surface roughness of such systems as well as the weight per square foot has heretofore required different revetment block designs to be used and intermixed in the grid matrix system. A mixture of different blocks with specificity increases the cost and complicates the establishment of a grid matrix system.
Today's revetment blocks cover a predetermined area and provide a predetermined static force which counters the hydraulic forces tending to move the blocks as the river waters pass thereover. The level of static force required and opposition to hydraulic uplift determines the size of the block to be used in a particular area of the grid matrix system. Again, different portions of the grid matrix system may require different block designs depending upon the particular hydraulic loads to be encountered in that portion of the system. As mentioned above, using different block designs complicates the overall design and furthermore increases the cost of the project.
Inhibiting the revetment blocks from moving relative to each other has resulted in revetment blocks which interconnect or interlock relative to each other. Heretofore known revetment blocks which interconnect with each other, however, are not provided with the ability to likewise easily adjust to changing ground contours. As will be appreciated, along an extensive length of a river or other waterway, the terrain over which the grid matrix system is arranged has a continuously changing ground contour. Thus, to accommodate the changes, the interlocking connections between the blocks have been broken off or dislocated thereby allowing the blocks to adjust to the changing ground contours. Of course, breaking off the interconnections defeats the ability of the blocks to interconnect and thus reverts to the problem of the blocks being displaced relative to each other or hydraulically undermined as a result of the hydraulic forces acting on the blocks.
Thus, there is a need and a desire for articulate revetment blocks which can be interconnected relative to each other to form a grid matrix system wherein the weight per square foot, static friction and surface roughness of the matrix system can be economically varied, as well as having the ability to modify the permeability of the system to accommodate specific requirements of different portions of the system.